In addition to reinforcing concrete internally with metal, it has been known to apply metal to the surface of concrete. In U.S. Pat. No. 1,898,864 a metal-faced building unit is prepared. The building unit is of a material such as concrete or cement. The metal facing, e.g., a steel facing, can be adhesively adhered to the concrete or cement body of the building unit.
Where the concrete is reinforced concrete, and the concern is corrosion of reinforcement embedded in the concrete, the metal applied to the concrete surface may be for retarding metal reinforcement corrosion. In U.S. Pat. No. 4,506,485, it is taught to flame spray an electrically conductive metal, e.g., zinc, onto a freshly exposed surface of concrete. The concrete can have steel embedded therein as reinforcement. The sprayed metal cover and embedded steel are joined in an electric circuit. Such means will be useful for precluding deterioration of the embedded reinforcement.
By covering a concrete surface with flame sprayed zinc and then electrically connecting the zinc with steel reinforcement of concrete, the assembly takes advantage of the sacrificial characteristic of the zinc to cathodically protect the embedded reinforcement. This leads to a gradual loss of zinc and loss of effectiveness of cathodic protection. It would be desirable to avoid or retard this loss.
It would be further desirable to provide a system that combines effective concrete-to-applied-metal bond strength, together with fast application and enhanced long term protection.